Metal coated article and process of manufacture thereof



1 Feb. 18, 1936. R ROBINSON ET AL 2,031,070

METAL COATED ARTICLE AND PROCESS OF MANUFACTURE THEREOF Filed May 17, 1933 Patented Feb. 18, 1936 I METAL COATED ARTICLE AND PROCESS OF MANUFACTURE THEREOF Robert It. Robinson Angeles, Calif.;

and EdwardL. Rick, Los said Rick assignor to William D. Howze, Los Angeles, Calif. Application May 17, 1933, Serial No. 671,516

25 Claims.

Our invention relates to metal coated articles, andin particular to such articles as signs in which designs or characters are applied as a metallic overlay upon a base of wood fibre or similar cellulose material. The invention also relates to the process of producing such an article so as to enable it to withstand continued exposure without noticeable deterioration.

It is a particular object of this invention to provide a sign capable of use in the electrical industries for designating ownership of towers,-

danger and high voltage signs etc. Many of such signs are required by law, and must be placed in out of the way locations that make replacementdiflicult and expensive. Long life is therefore essential. Furthermore, as such'signs are often made thetarget for hunters, as-well as for small boys who delight in pelting them with.rocks and shooting at them with rifles and airguns, they must sustain such misuse with minimum damage. Vitreous enamel signs often used for this purpose, shatter under such impacts, exposing the metal beneath, and destroying the readability of the sign. Such a sign asherein described of non-metallic body is of great value,

as it will not cause radio interference, does not require grounding, and can be safely handled in high voltage fields. Small bulk and weight-is another requisite, as repair wagons must carry large quantities of these signs.

It is therefore an object of this invention to provide such a sign of thin section, of high insulation value and light weight, which will withstand the roughest sort of handling and misuse without material damage, which will be noncorrosive and permanent under all. sorts of weather conditions and which will have a long life of readability;

A further object is to provide a process for the manufacture of such a sign and similar articles which will have the advantages above set forth, in particular whereby a wood fibre or similar surface may be prepared for the bonding thereto in a permanent manner ofmetals applied in molten state, and whereby the metal so applied will become an integral part of the body to which it is applied. A further object is the treatment of such a sign in a manner to eliminate the access of moisture to the bond surfaces, and to seal the body of the sign against subsequent moisture absorption. It is a further ob- Ject to provide. a unique method of preparing the surface of a cellulose body upon which metal -is to be deposited whereby it will be free of 55 moisture, oil, andother inherent and extraneous \gggis first subjected to alight'sand blast as in substances or characteristics which could prevent, proper bonding of the metal thereto.

Other advantages Will be seen to obviously result from the provision of such a sign as described in the accompanying specification, and 5 the process of manufacture thereof also described therein.

In the drawing, which shows but one embodiment of the invention and illustrates the various -steps utilized in the process of producing such 10 embodiment:

Fig. I is a face view of a sign made in accordance with this invention.

Fig. 2 is a section taken on line 22 of Fig. 1.

Fig. 3 is an enlarged fragmentary view of the 16 surface of the material used prior to treatment thereof. g

Fig. 3a illustrates a method of preliminary surface treatment used on smooth surfaces of the body material. Y 20 Fig. 4 illustrates one method of heat treating" the surface of the body material. A 1

Fig. 5 illustrates the method used in applyingthe "metallic lettering.

Figures 6, 7, 8, and 9 illustrate subsequent steps 25 the process of manufacture of the signs. The body. ll of the sign is preferably composed ofcompounded woodfibre, one form of which is commonly known as pressed wood or grainless wood". This material is manufac- 30 "tured'from wood chips and-shavings, exploded by steam into individual fibres, which are subsequently conditioned, graded, and recombined under-heat and high pressure into highly compressed sheets. ural lignins and-resins of the wood are brought out under the ..heat and pressure and serve as a binder. A paraffin oil is added for moistureproofing. The sheets are pressed between smooth platens and wire screens, so that as received one 40 side Ila is'glazed and smooth, and the opposite side Ilb rough, fibrous, and irregular in appearance, and covered with impressions I 2 from the-screen. This side is illustratedfin Fig. 3.

Preparation of the surfaces for thereception 45 of the metal lettering is therefore accomplished in two ways. When the smooth side is to be used.

3a.- Thereafter treatment of either side is he same, The is next heat treated such as rapidly passing over the surface with an oxyacetylene flame I3 as inFig. 4. The intensely hot flame so obtained permits a rapid semi-carbonization of the surface, searing and thus sealing it with the 55 No binder is-used, but the nat- 35.

natural resins and lignins from the heated wood fibres; burning off the small fibrous fuzz on the rough surface as well as the sawdust and milldust, etc., which are present in varying amounts; driving off the moisture and oils from the surface; all without allowing the heat time to penetrate into the material with sufficient intensity to injure the fibres inside. The surface is but partially carbonized, giving a permanent black-' brown color, and is sufilciently changed inchar acter from the somewhat soft, rough, fibrous original character of the surface to a dense, hard,

resinous, oil and moisture-free base layer 110,

as to provide an ideal medium for the reception of the subsequently applied metal. I v

Prior to such partial carbonizatio'n, each wood fibre on the surface is distinctly visible through a low power glass. Afterwards the separate fibers are not distinguishable even with a high power 1 glass, the separate fibres seemingly having been fused together into a compact, hard, surface. After a light brushing to remove the completely carbonized dust and fuzz, there is not sufilcient free carbon in the surface to color a white cloth 'rubbed over it.

Other treatments prior to heat treating are used for particular effects. For an intense brilliant black background, the surface is dampened with a sugar solution. Other substances can also be successfully combined with the resinous surface during the heat treatment such as dyes resin-producing powders, and certain oils. In each case subsequent rapid, high temperature heating is used to properly change the character brushed or wiped to remove carbon dust, and.then

placed upon a jig board I 4 having suitable provision thereon for the locating of the sign body in conjunction with cooperating stencils l5 and I511. A metal spray gun J6, with connections for oxygen, acetylene or hydrogen, and air, and-supplied with metal in the form, of wire, .is utilized to deposit metal through- .the stencils to form 'the'metal lettering ll upon the sign.

Stencil I5 is of paper or cardboard, and is held in 'close contact withthe sign body H, and retained against the forces of the gases from the metal spray gun,- by the rnetal stencil l5a. Suitable clamps, not, shown,clamp the stencil l5a against the stencil l5 and the body ll to the jig board It. Centers of the various letters, such as-the portion I8 of the-A and IQ of; the 0 are covered by. metal center pieces2l supported on the bridging 20 of the metal stencil 15a. The openings in the metal stencil are slightly, larger than the corresponding openings'in the paper stencil I5, and thus allow for the collection of metal particles on the metal stencil without interference with the sharp boundary, line of the applied letters. The paper stencilsarej'dis:

carded after' using two or three tin'ies; The center pieces 2i are clea ed'by the operator when metal collects upon them. The metal stencil is ins.

partially protected by a resist such as soap or a thin oil or graphite.

' The metal spray gun l6 utilizes the so-called Schoop process to deposit a thin coating of relatively impervious metal through the stencil openings. The gun is supplied with air at-about pounds pressure. The metal to be applied, in wire form, is fed into the heart of the oxy-acetylene flame. A blast of air is focused upon it at this point, atomizing. the molten metal and carrying it at high velocity against the surface of the sign.

The impact of the molten metal is sufficient to I make it adhere tightly to the surface, keying itself intojevery' crevice. A coating from two to five thousandths of an inch thick is used. Preferably, the lettering is aluminum, although zinc,

' tin, and other metals obtainable in wire form may be used.

Although the oxy-acetylene or oxy-hydrogen flame is used in this process, the material being coated is not subject to high heat. The high velocity air blast keeps the material comparatively cool. The molten metal does not have time to cool and solidify between the melting point in the flame and its deposition on the material and thus carries its heat directly to the point of impact. Careful examination of the product under the glass indicates that this heat is sufficient to slightly soften the surface previously "resinized by the heat treatment, and that the initial particles of molten metal actually imbed themselves into this surface. Other tests have shown that the metal cannot be mechanically removed without also taking away this resinized surface layer.

Cellulose compounds and wooden articles have heretofore been coated with metal by this Schoop processfafter prior sand blasting. Results are very uncertain when attempting to apply coatings to wood, owing to the moisture, oils' and resins in the wood, and the gases formed in the wood when heated even by the air-cooled flame. By the herein described surface pre-heating process, coatings. are applied to such surfaces without dif ficulty.

, Further, such coatings as have been successful have been unbroken coatings, completely cover-' ing the wooden article to be coated. Intermittent coatings have not been successful, moisture being carried to the bond juncture of wood and metal through the wood fibres and destroying what bond might there exist. Transparent protective oil, lacquer and varnish coatings are, effective in exeluding moisture only for a limited period. Shrinkage'or expansion of the base material due to moisture, freezing, and other atmospheric changes also will cause peeling of the metal coat- The process herein described has produced metal coatings, which, unprotected'by any oil, varnish, lacquer or similar material, have withstood months of outdoor exposure without any visible deterioration. Such coatings were intermittent, such as the sign illustrated, in which there were areas of exposed heat treated wood fibre surface adjacent the areas coated. v

As a further protection and safeguard, after the metal lettering has been applied, the signs are soaked for a period of approximately thirty minutes in a sealing oil mixture 22, containing linseed oil, soya bean oil, turpentine and other vegetable oils, know, to the trade as lionoil. This oil is of a thin consistency and readily penetrates the pores of the body material, and dries to a gummy, elastic consistency with fair rapidity.

' stices between the fibres filled tallic indicia adhering to such surface through the intimacy of. the contact therewith; coating a cellulose body with Even when dry, it is still elastic and somewhat gummy and sticky. Suitable racks 22a are used to keep the signs separated during the soaking period, after which the racks are up-ended and the signs allowed to drain for about ten minutes as shown in Fig. 7. They are then wiped or squeeged such as by a slightly resilient wiper 23, (see Fig. 8) to remove the oil from the face of the metal letters and to distribute the excess oil along the edges of the letters and into the depressions in the face thereof where porous spots in the metal might occur. After such wiping the signs are hung on hook racks 24 for drymg.

Since any moisture in the sign body II has been driven out by the pre-heating during carbonization of the surface, oil is-absorbed into the pores from which the moisture was driven during the soaking process.. The oil gums noticeably during the ten minute draining period, so that the subsequent superficial wiping removes but little oil except from the non-absorptive metal surface.

A noticeable increases in transverse strength is obtained by the soaking in oil.

The sealing action of the oil is particularly advantageous along the edges of the letters such as at 25, Fig. 2. It is here if at all that defects in the metal applicationand bonding are apt to occur, such as are caused by paper particles from the stencil l5, loosened by the air blast, adherence of the metal to the paper stencil, etc. As the metal is overlayed, there is a. noticeable edge along each letter,and during the wiping, excess oil collects along this edge. The oil also will seep through any porous spots in the metal coating, as at 26, and seal the pores beneath against the entrance of moisture.

Particular features of the material used are .that, being compounded from short exploded wood fibres, the fibres of the wood are not continuous, as in natural wood, and withthe interwith oil, moisture is not transmitted through the body, even though it may enter the exposed edges. Consequently the body does not check, crack. or weather as does natural wood; Likewise the screen depressions l2 provide a large key-hold for the sprayed metal as well as giving depressed areas of tend to prevent serious injury from rubbing against each other during transportation, as well as from the sand-blasting action of wind blown sand in desert areas. The signs retain their readability, even though the high spots are abraded away.

Having thus disclosed our invention, we claim and desire to secure by Letters'Patent:

.1. A sign including a cellulose body and metallieindicia adhering toasurface thereof primarily through the intimacy of the contact therewith. ,3

-2. A sign. including a cellulose body and metallic indicia adhering to a surface thereof primarily through the intimacy of the contact therewith, the cellulose material of said body being porous and a sealing compound impregnating the intersticesof said body. '3. A sign including a body of compounded wood fibre having a portion of the volatizable matter removed from a surface of said body, and meprimarily .4. The process of metal which includes removing 'a' portion of the volatizable matter from the surface of said body molten metal metal which abrasion by and subsequently directing molten metal particles thereagainst at high velocity.

5. The process of coating a cellulose body with metal which includes exposing a surface thereof to a high temperature and subsequently directing particles thereagainst at high velocity.

6. The process of coating a cellulose body with metal which includes heating said body sufiiciently to drive volatizable matter therefrom, directing molten metal particles thereagainst at high velocity, and thereafter soaking said bodyin a sealing mixture.

7. The process of producing a sign which includes charring the surface of a wood fibre body, directing molten metal particles thereagainst at high velocity while protecting certain surfaces thereof, soaking said body in a sealing mixture, and prior to the final drying thereof, redistributing the sealing mixture across the surface thereof.

8. A sign including a body of compressed carbonaceous material having a roughened surface, said surface being partially carbonized, and metallic indicia adhering thereto primarily through,

intimacy of contact therewith.

bonaceous material, having a roughened surface, said surface being partially carbonized, a portion of the volatizable matter normally in said body material having been expelled therefrom, metallic indicia consisting of a relatively 'thin layer of metal 'upon said surface adhering thereto primarily through the intimacy of contact therewith, and a sealing oil impregnating said body and covering the surfaces of said sign.

10. A sign including a body of compressed wood fibre and indicia comprising a thin layer of aluminum adhering thereto primarily through the intimacy of contact therewith.

11. A sign as described in claim 10 impregnated with a resinous oil.

12. The process of coating a carbonaceous body with metal which includes; roughening a surface thereof, partially carbonizing said surface, expelling moisture from said body, applying a thin layer of metal thereto by melting said metal and atomizing the same into a high velocity spray. directed against said surface, and soaking said body in a sealing oil.

13. The process of coating a carbonaceous material with metal which includes passing a high temperature flame across the surface thereof, and

16. A sign comprising a base of cellulose fibre,

a portion of the volatile constituent thereof having been expelled from a surface thereof, and metallic indicia bonded to such surface primarily through intimacy of contact therewith.

17. Asign as described in claim 16 and including a resinous oil impregnating such body and filling the interstices thereof from which volatile constituents have been expelled whereby the subof said surface and having projections thereon corresponding with said depressions, said metallic indicia adhering to said body primarily through intimacy of contact therewith, -'the corresponding projections and depressions forming spaced anchoring points for each character of said indicia.

' 19. A sign comprising a base of cellulose fibre,

and metallic indicia adhering to a surface of saidbody primarily through intimacy of contact therewith, said indicia being of such relative thinness as to appear after application substantiallyflush with said surface.

20. The process of coating a cellulose base article with metal which includes heating the surface to be coated at a high temperature for a relatively short time interval, whereby volatizable constituents are expelled from such surface without v complete carbonization thereof, applying the metal in a molten high velocity spray, and subsequently filling the interstices caused by such volatization with a sealing oil by soaking the article therein.

21. A sign as described in claim 18 in which said surface is partially carbonized.

22. A sign as described in claim 18- in which said cellulose fibre has -a portion of its volatile constituents removed andv including a sealing material impregnating the interstices of said body from which such volatile material has been expelled.

23. A sign as described in claim 1 in which said surface is partially carbonized. I

24. A sign comprising a body of fibrous insulating material .and metallic lndicia adhering to a surface thereof primarily through intimacy of contact therewith.

25. A sign as described in claim 24 and including a waterproof sealing material filling the spaces between the fibers of such insulating material.

ROBERT R. ROBINSON. EDWARD L. RICK. 

